In recent years, with the multimediatization of information in mobile communication systems, transmitting high capacity data such as still images and movies in addition to speech data has become popular. To realize the transmission of high capacity data, a technology in which a high-frequency radio band is used to provide a high transmission rate is studied.
However, when a high-frequency radio band is used, although a high transmission rate can be expected in a short distance, attenuation due to transmission distance becomes greater as the distance increases. Accordingly, when the mobile communication system employing a high-frequency radio band is operated, the coverage area of a radio communication base station apparatus (hereinafter “base station”) becomes small, which requires that a larger number of base stations be set up in order to prevent the service area from reducing. Since the set-up of base stations involves large costs, a technology is strongly demanded for realizing communication services which employ a high-frequency radio band and for preventing an increase in the number of base stations.
To meet this demand, in order to expand coverage areas of base stations, relay transmission technologies are investigated in which a radio communication relay station apparatus (hereinafter “relay station”) is set up between a radio communication mobile station apparatus (hereinafter “mobile station”) and a base station, and in which communication between the mobile station and the base station is carried out via the relay station.
Meanwhile, in future mobile communication systems, studies will be conducted for services in which the base station employing various RATs (Radio Access Technologies) such as W-CDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), WLAN (Wireless LAN), and WiMAX (Worldwide interoperability for Microwave Access) distributes information related to a specific area (i.e. specific area information) to that specific area in a coverage area of the base station. Then, with regards to these services, a mobile station needs to detect in which base station's coverage area the mobile station is currently located and which area's specific area information the mobile station can receive. For example, when part of a base station's coverage area includes a specific area, a mobile station located in the specific area cannot receive specific area information unless the mobile station is able to detect that the mobile station is located in the specific area.
Conventionally, Patent Document 1 discloses a technique of storing specific area information on a specific area in a coverage area of a base station under the base station control apparatus in memory, and of constantly transmitting the stored specific area information via the base station. A mobile station located inside the specific area then receives specific area information and shows the received information on a display. In this case, the mobile station switches a frequency band to the frequency band in which the base station transmits the specific area information, and receives the specific area information.    Patent Document 1: Japanese Patent Application Laid-Open No. 2001-169355